Re: OSTree and OCI images

[Colin Walters <walters verbum org>]

On Thu, Nov 24, 2016, at 03:52 AM, Alexander Larsson wrote:
> For flatpak, these are the OCI operations we currently support:
>
>  * Export a (non-layered) branch (flatpak app) as an OCI image in an
>    OCI directory layout. This is "flatpak build-bundle --oci" in the
>    current code. In addition to just dumping the ostree content
>    as a tarball layer this adds enough ostree specific commit metadata
>    to the image that the ostree commit can be reconstructed with the
>    same commit id at a later point.

Okay, so at a high level, we're exporting to a tarball, and relying
on importing-via-ostree to result in the same "contents" (dirtree/dirmeta),
in git this would be just a "tree" object.

Honestly, I hadn't even thought of doing that - I'd been envisioning
archive-repo-in-tar, or delta-in-tar.

The advantages of "tar translation" is that tools will show you something
reasonable when looking at the archive.

The downsides are that we have to re-checksum everything on
import.  But eh.

To have a shorthand, let's call this format "ostree-exported-oci".  Or
maybe "ocitreear"? =)

> *  Import an OCI image from an local directory into a (non-
>    layered) ostree branch, merging multiple layers in the
>    source image, and also applying any optional ostree specific 
>    metadata in the image. This is "flatpak build-import-bundle --oci"
>    in the current code.

Do you have any use case in flatpak for importing OCI images
that aren't ostree-exported-oci?

You seem to imply below you do, but can you be specific?  Is
this something like being able to auto-import a desktop app
someone did in Docker/OCI into flatpak?